Support frame assemblies of the type with which this invention is concerned are often used in regions in which a generally horizontal support surface may undulate, at least to some extent, that renders conventional supporting frame assemblies that employ rigid trusses arranged in a polygonal configuration inappropriate or, at least to some extent ineffective, in view of the different heights at which different parts of a supporting frame assembly become supported.
A conventional rigid truss may be composed of a pair of parallel spaced frame members interconnected by multiple diagonal braces or struts that together form a rigid and unyielding truss. Typically the ends of a truss are rigidly connected to an item being supported by the frame. In instances in which the item being supported is required to be in a generally particular orientation, such as generally upright in the case of a pylon, such an arrangement does not work effectively.
For example, in the instance of a supporting frame to which a pylon supported heliostat is attached, the focusing of reflected solar energy accurately towards a central tower receiver is imperative and consequently the stability of the supporting frame and pylon must ensure the necessary accuracy that in turn depends on the stability of the supporting frame and pylon. Also, it should be noted that support structures for the heliostats in such an application are responsible for an appreciable proportion of the capital expenditure on an entire installation.
In consequence of this, the development of more stable and less costly support structures has been an ongoing challenge and one support structure that has been evolved forms the subject matter of our published international patent application WO2014072905. As shown in accompanying FIG. 1, the support structure in that instance provides a supporting frame supporting a stable pylon (A) for each heliostat (B) and the pylons are arranged in a triangular pattern with the pylons being secured together by girders (C), preferably in the form of trusses, secured to projecting plates (D) welded to the pylons and forming a framework therewith. It is considered that this arrangement will work effectively when installed on relatively even ground but may be somewhat problematical on at least some types of undulating ground. It also involves a significant amount of welding that contributes to the cost of the support structure and welds require additional corrosion protection. The latter applies particularly to the type of trusses employed.
It is considered that there is yet appreciable scope for improvement in an arrangement of pylons and a supporting frame for purposes such as this or for supporting any other items such as those identified above.
The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application.